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Undifferentiated Connective-Tissue Disease (Overview)

eMedicine.com, 2011

Introduction Background Many connective-tissue diseases (CTDs) share common signs and symptoms, which frequently makes the diagnosis of a specific rheumatic disease difficult.
Rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), systemic sclerosis (SSc), polymyositis (PM), dermatomyositis (DM), mixed connective-tissue disease (MCTD), and Sjögren syndrome (SS) can present with similar clinical features, particularly during the first 12 months of symptoms.
Isolated Raynaud phenomenon, inflammatory polyarthritis, anemia, interstitial lung disease, or pleuropericarditis may occur without an obvious diagnosis.
Screening serology findings, such as rheumatoid factor (RF) or antinuclear antibody (ANA), may be positive or negative under these clinical circumstances.
Patients who present with symptoms, positive serology results, or physical findings consistent with an established connective-tissue disease but not fulfilling classification criteria for one of these established connective-tissue diseases are diagnosed with undifferentiated connective-tissue disease (UCTD).
Mosca et al recently reviewed UCTD literature and proposed that preliminary classification criteria include (1) signs and symptoms suggestive of a connective-tissue disease, (2) positive ANA results, and (3) a disease that lasts at least 3 years.
Pathophysiology The pathophysiology of most connective-tissue diseases is unclear, and UCTD is no different in this respect.
The presence of autoantibodies commonly precedes disease onset, suggesting that they are not secondary to tissue damage or disease expression.
Therefore, autoantibodies may be etiopathogenic or may only be clinical markers of the disease process.
Like most connective-tissue diseases, the theory and research have been concentrated on genetically susceptible hosts, T- and B-cell abnormalities, and environmental triggers, such as ultraviolet light or infection.
Recent studies into specific antibodies associated with UCTD have demonstrated significant correspondence with anti-HSP60 and anti-HSP65 antibodies, as well as anti-Sp1 antibodies; however, further research is needed to evaluate the implications of these associations further.